1 66 



THE GERM-CELLS 



consisting of three parts, lying side by side in the cytoplasm (Fig. 83). 

 These are {a)2i colourless sphere, shown by Meves's later researches to 

 be probably an attraction-sphere ; (/^) a minute, intensely staining cor- 

 puscle, and ((•) a small, deeply staining ring. The concurrent results 

 of Hermann ('89, '92, '97), IkMula ('93), and Meves ('96, '97, 2) have 

 shown that the small corpuscle (r) is one of the ccutrosoDies of tlie 

 spcnnatiti, and all these observers agree that it passes into or gives 



Fig. 84. — Formation of the spermatozoon in Amphibia. \^A-E. Salaviandra, MEVES; 

 F-K. Aiiiphiiinta, McGkkijok,] 



A. Spermatid with peripheral pair of centrosomes lying outside the sphere, and axial filament. 

 B. Centrosomes near the nucleus, outer one ring-shaped. C. Inner centrosome inside the 

 nucleus, enlarging to form middle-piece. D. Portion of much older spermatid, showing divergence 

 of two halves of the ring (/-). E. Portion of mature spermatozoon, showing upper half of ring at 

 r, and the axial filament proceeding from it. 



F. Spermatid of ^;;///////wa, showing sphere-bridges and ring-shaped mid-bodies. G. Later 

 stage; outer centrosome ring-shaped, inner one double; sphere {s) converted into the acrosome. 

 //. Migration of the centrosomes. /. Middle-piece at base of nucleus, y. The inner centrosome 

 forms the end-knob within the middle-piece, which is now inside the nucleus. K. Enlargement of 

 middle-piece, end-knob within it; elongation of the ring. 



